STUDIES ON PATHOLOGY OF SHEEP LUNG
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Date
2007-01
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT:
In a developing agriculture based country like ours more than 70
crores of people are solely depend on agriculture and livestock and
contributing more than 20% of G.D.P. annually. India ranks 6" among
the countries of world with a population of 138.50 million sheep and
Andrapradesh ranks IS' place in India with a sheep population of 21.37
millions. Lung infections are common in sheep, causing a great threat
to the sheep rearing community. As disease problems severely cripples the production, a sound
knowledge of common contagious or infectious diseases that accounts
for morbidity and mortality in sheep become necessity.
Keeping this in view, the present study on 'Studies on
pathology of sheep lung' was undertaken to investigate various lung
infections and isolation of bacteria those cause pneumonia in sheep
and to know the ultra structural changes of pulmonary adenomatosis.
Incidence of various types of pneumonia encountered were due
bronchopneumonia (28%), pulmonary adenomatosis (9.8%),
suppurative pneumonia (8.3%), interstial pneumonia (7.8%),
fibrinous pneumonia (7.3%), Maedi (5.3%), pleuropneumonia
(2.2%), hydatid cyst (1.26%), Sheep pox (1.0%), Tuberculosis
(1 .OO/o), and neoplasm's like hemangioma and adenocarcinoma,
noticed in two cases with an incidence of (0.5%)
Bronchopneumonia was characterized by presence of moderate
to severe infiltration of inflammatory cells, neutrophils and
mononuclear cells in and around bronchioles and alveoli. Inter alveolar
hemorrhages with mild edema of alveoli and peribronchial
hemorrhages were seen. Pulmonary adenomatosis was characterized by papillary
projections of epithelium into alveolar/ bronchiolar lumen. Fibrous
tissue proliferation was seen. Metaplasia of alveolar epithelium leading
to formation of glandular structures in alveoli was also evident.
Suppurative pneumonia was characterized by areas of
congestion, necrosis with calcification and presence of diffuse
infiltration of inflammatory cells, mostly neutrophils and alveolar
macrophages. Fibrous tissue proliferation was also evident.
Interstitial pneumonia was characterized by thickened alveolar
septa due to accumulation of serous and fibrinous exudates with
infiltration of inflammatory cells like lymphocytes, macrophages and
mononuclear cells in alveolar septa. In fibrinous pneumonia alveoli, bronchioles and bronchi were
filled with sero fibrinous exudate. Infiltration of inflammatory cells
like neutrophils and macrophages were seen along with edema,
congestion and hemorrhages. Edema and widening of inter lobular
septa was noticed in almost all cases with thickening of pleura.
Maedi was characterized by hypertrophy and hyperplasia of
bronchiolar epithelium. Peribronchiolar and perivascular infiltration
with lymphocytes was most predominantly seen. Alveolar lumen
contained desquamated epithelial cells. A thickened alveolar wall with
interalveolar hemorrhages were also evident. Pleuro pneumonia was characterized by active hyperemia
edema, congestion and hemorrhages with mild serous exudates along
with mild infiltration of inflammatory cells like rnacrophages,
lymphocytes and epitheloid cells. The pleura was thickened with
fibrous tissue proliferation. Infiltration was very mild with neutrophiis
and lymphocytes Tuberculosis was characterized by a granuloma with a central
caseation and calcification surrounded by macrophages, epitheloid
cells, lymphocytes, and Langhan's giant cells surrounded by fibrous
covering. Other changes noticed were thickened pleura, sub pleural
hemorrhages, pleural fibrosis and congestion. Hydatidosis was characterized by presence of mononuclear
cells, eosinophils and plasma cell infiltration around the cystic space
and surrounded by focal areas of fibrous tissue proliferation along with
hemorrhages and congestion. Sheep pox was characterized by coagulative necrosis of the
lobular tissue and infiltrated with the inflammatory cells mainly 'sheep
pox' cells and macrophages and presence of serous exudate. The
adjacent lung tissue showed congestion and infiltration with
lymphocytes, neutrophils and macrophages. Neoplasms like
hemangioma and adenocarcinoma were noticed in one case each.
General pathological conditions encountered were pleuritis 2
(0.5%), bronchitis and bronchiolitis 15 (3.7%), bronchiectasis 2
(0.5%), bronchiolitis fibrosa oblitrans 2 (0.5%), pulmonary
congestion and hemorrhages 17 (4.2%), pulmonary emphysema and
atelectasis 16 (4.5%), pulmonary edema 16 (4.5%), pulmonary
infarction 1 (0.2%), and anthracosis 1 (0.2%).
Pleuritis was characterized by infiltration of inflammatory cells
like neutophils and lymphocytes in the pleura and thickening of the
pleura by edematous fluid. Bronchitis and bronchiolitis were characterized by presence of
inflammatory cells like neutrophils, mononuclear cells and
erythrocytes in the bronchi and bronchioles and these conditions were
usually associated with bronchopneumonia. Widened lumen of bronchi contained mucus, large number of
inflammatory cells, few erythrocytes. Bronchiolar wall was very thin
and surrounded by fibrous tissue proliferation in bronchiectasis cases.
Bronchiolitis fibrosa oblitranse was characterized by polypoid
projections of bronchiolar epithelial and fibroblastic tissue, which was
partially or completely, obliterated the lumen of bronchioles.
Hemomes in the alveolar and bronchial spaces were noticed
in pulmonary congestion and hemorrhages. Pulmonary emphysema
was characterized by distended alveoli, widened interalveolar septa;
few ruptured alveoli and atelectatic areas were characterized by cleft
like alveoli with narrow lumen. Pulmonary edema was characterized by presence of edema fluid
in the alveoli, interstitial tissue, interlobular septa and sub pleural zones
and presence of compensatory emphysema and atelectatic changes.
Pulmonary infarction revealed wedge or cone shaped
hemorrhagic areas and presence of congestion, edema and atelectasis.
Anthracosis was characterized by presence of black granules mostly in
the alveolar walls and connective tissue septa of lung.
In the present study 44 bacteria were isolated fiom 57
pneumonic ovine lungs. Pasteurella sps 10 (22.7%), E.coli 7 (1 5.9%),
Corynebacterium sps 6 (13.6%), and Staphylococcus sps 6 (13.6%),
were the major bacteria isolated. Stray cases of isolates were
Streptococcus 3 (6.8%), Bacillus sps 2 (4.5%), Klebsiella sps 2 (4.5%),
Proteus sps 2 (4.5%), Mjcobacterium 4 (9.0%), and Pseudomomis sps
2 (4.5%) cases. Major bacteria isolated fkom bronchopneumonia were
Pastewella sps, followed by E-coli, Corynebacterium, and
StaphyIococcal sps and from suppurative and fibrinous pneumonia
cases, PasteureZla, E-coli. Corynebacterium were isolated. From
pulmonary carcinoma, E. coli, Staphylococcus, Streptococcus was
isolated and mycobacterium was identified in tuberculosis lung.
Ultrastructurally, in all the cases of pulmonary adenomatosis
proliferation of type I1 pneumocytes having microvilli, well-developed
junctional complexes were noticed prominently. Mitochondria and
endoplasmic reticulum were more numerous in type I1 penumocytes. In
most of the cases mitochondria were well preserved with prominent
cristae. Ciliated bronchiolar (Clara) cells with electron dense
cytoplasmic granules without any surrounding membrane and
microvilli were noticed.
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